B2.1.3 Active Transport

Question 1

What is active transport?

Answer 1

Active transport allows cells to move substances from an area of low concentration to an area of high concentration
Movement of particles against the concentration gradient requires energy

Question 2

What are the three key features of active transport?

Answer 2

Particles are transported against a concentration gradient
ATP is required - comes from respiration
The process makes use of carrier proteins in the cell membrane

Question 3

State why energy must be transferred from an energy store in active transport:

Answer 3

As the particles are moving against the concentration gradient

Question 4

What are carrier proteins

Answer 4

Special proteins that stretch across the width of the cell membrane
A particular molecule that the cell requires binds to a specific carrier protein

Question 5

Explain why plants use active transport, rather than diffusion, to absorb minerals from the soil. (4)

Answer 5

They cannot be absorbed by diffusion, since the minerals are very low in concentration.
Instead, active transport is used.
The root hair cells have carrier proteins in their cell membranes.
These pick up the mineral ions and move them across the membrane into the cell against the concentration gradient .

Question 6

State two differences between diffusion and active transport:

Answer 6

• diffusion is the movement of particles from a region of high concentration to low whereas active transport allows cells to move substances from an area of low concentration to high concentration
• diffusion is a passive process meaning it doesn’t require energy whereas active transport does, in the form of ATP